/********************************************************************** 

    Golgotha Forever - A portable, free 3D strategy and FPS game.
    Copyright (C) 1999 Golgotha Forever Developers

    Sources contained in this distribution were derived from
    Crack Dot Com's public release of Golgotha which can be
    found here:  http://www.crack.com

    All changes and new works are licensed under the GPL:

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    For the full license, see COPYING.

***********************************************************************/
 

/* 
 * Mpeg Layer-2 audio decoder 
 * --------------------------
 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
 *
 */

#include "loaders/mp3/mpg123.hh"

static int grp_3tab[32 * 3] = { 0, };   /* used: 27 */
static int grp_5tab[128 * 3] = { 0, };  /* used: 125 */
static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */

real muls[27][64];	/* also used by layer 1 */

void init_layer2(void)
{
  static double mulmul[27] = {
    0.0 , -2.0/3.0 , 2.0/3.0 ,
    2.0/7.0 , 2.0/15.0 , 2.0/31.0, 2.0/63.0 , 2.0/127.0 , 2.0/255.0 ,
    2.0/511.0 , 2.0/1023.0 , 2.0/2047.0 , 2.0/4095.0 , 2.0/8191.0 ,
    2.0/16383.0 , 2.0/32767.0 , 2.0/65535.0 ,
    -4.0/5.0 , -2.0/5.0 , 2.0/5.0, 4.0/5.0 ,
    -8.0/9.0 , -4.0/9.0 , -2.0/9.0 , 2.0/9.0 , 4.0/9.0 , 8.0/9.0 };
  static int base[3][9] = {
     { 1 , 0, 2 , } ,
     { 17, 18, 0 , 19, 20 , } ,
     { 21, 1, 22, 23, 0, 24, 25, 2, 26 } };
  int i,j,k,l,len;
  real *table;
  static int tablen[3] = { 3 , 5 , 9 };
  static int *itable,*tables[3] = { grp_3tab , grp_5tab , grp_9tab };

	memset(grp_3tab, 0, sizeof(grp_3tab));
	memset(grp_5tab, 0, sizeof(grp_5tab));
	memset(grp_9tab, 0, sizeof(grp_9tab));
	memset(grp_9tab, 0, sizeof(grp_9tab));

  for(i=0;i<3;i++)
  {
    itable = tables[i];
    len = tablen[i];
    for(j=0;j<len;j++)
      for(k=0;k<len;k++)
        for(l=0;l<len;l++)
        {
          *itable++ = base[i][l];
          *itable++ = base[i][k];
          *itable++ = base[i][j];
        }
  }

  for(k=0;k<27;k++)
  {
    double m=mulmul[k];
    table = muls[k];
    for(j=3,i=0;i<63;i++,j--)
      *table++ = m * pow(2.0,(double) j / 3.0);
    *table++ = 0.0;
  }
}


void II_step_one(unsigned int *bit_alloc,int *scale,struct frame *fr)
{
    int stereo = fr->stereo-1;
    int sblimit = fr->II_sblimit;
    int jsbound = fr->jsbound;
    int sblimit2 = fr->II_sblimit<<stereo;
    struct al_table *alloc1 = fr->alloc;
    int i;
    unsigned int *scfsi,*bita;
    int sc,step;
		static unsigned int scfsi_buf[64];

    bita = bit_alloc;
    if(stereo)
    {
      for (i=jsbound;i;i--,alloc1+=(1<<step))
      {
        *bita++ = (char) getbits(step=alloc1->bits);
        *bita++ = (char) getbits(step);
      }
      for (i=sblimit-jsbound;i;i--,alloc1+=(1<<step))
      {
        bita[0] = (char) getbits(step=alloc1->bits);
        bita[1] = bita[0];
        bita+=2;
      }
      bita = bit_alloc;
      scfsi=scfsi_buf;
      for (i=sblimit2;i;i--)
        if (*bita++)
          *scfsi++ = (char) getbits_fast(2);
    }
    else /* mono */
    {
      for (i=sblimit;i;i--,alloc1+=(1<<step))
        *bita++ = (char) getbits(step=alloc1->bits);
      bita = bit_alloc;
      scfsi=scfsi_buf;
      for (i=sblimit;i;i--)
        if (*bita++)
          *scfsi++ = (char) getbits_fast(2);
    }

    bita = bit_alloc;
    scfsi=scfsi_buf;
    for (i=sblimit2;i;i--) 
      if (*bita++)
        switch (*scfsi++) 
        {
          case 0: 
                *scale++ = getbits_fast(6);
                *scale++ = getbits_fast(6);
                *scale++ = getbits_fast(6);
                break;
          case 1 : 
                *scale++ = sc = getbits_fast(6);
                *scale++ = sc;
                *scale++ = getbits_fast(6);
                break;
          case 2: 
                *scale++ = sc = getbits_fast(6);
                *scale++ = sc;
                *scale++ = sc;
                break;
          default:              /* case 3 */
                *scale++ = getbits_fast(6);
                *scale++ = sc = getbits_fast(6);
                *scale++ = sc;
                break;
        }

}

void II_step_two(unsigned int *bit_alloc,real fraction[2][4][SBLIMIT],int *scale,struct frame *fr,int x1)
{
    int i,j,k,ba;
    int stereo = fr->stereo;
    int sblimit = fr->II_sblimit;
    int jsbound = fr->jsbound;
    struct al_table *alloc2,*alloc1 = fr->alloc;
    unsigned int *bita=bit_alloc;
    int d1,step;

    for (i=0;i<jsbound;i++,alloc1+=(1<<step))
    {
      step = alloc1->bits;
      for (j=0;j<stereo;j++)
      {
        if ( (ba=*bita++) ) 
        {
          k=(alloc2 = alloc1+ba)->bits;
          if( (d1=alloc2->d) < 0) 
          {
            real cm=muls[k][scale[x1]];
            fraction[j][0][i] = ((real) ((int)getbits(k) + d1)) * cm;
            fraction[j][1][i] = ((real) ((int)getbits(k) + d1)) * cm;
            fraction[j][2][i] = ((real) ((int)getbits(k) + d1)) * cm;
          }        
          else 
          {
            static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
            unsigned int idx,*tab,m=scale[x1];
            idx = (unsigned int) getbits(k);
            tab = (unsigned int *) (table[d1] + idx + idx + idx);
            fraction[j][0][i] = muls[*tab++][m];
            fraction[j][1][i] = muls[*tab++][m];
            fraction[j][2][i] = muls[*tab][m];  
          }
          scale+=3;
        }
        else
          fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
      }
    }

    for (i=jsbound;i<sblimit;i++,alloc1+=(1<<step))
    {
      step = alloc1->bits;
      bita++;	/* channel 1 and channel 2 bitalloc are the same */
      if ( (ba=*bita++) )
      {
        k=(alloc2 = alloc1+ba)->bits;
        if( (d1=alloc2->d) < 0)
        {
          real cm;
          cm=muls[k][scale[x1+3]];
          fraction[1][0][i] = (fraction[0][0][i] = (real) ((int)getbits(k) + d1) ) * cm;
          fraction[1][1][i] = (fraction[0][1][i] = (real) ((int)getbits(k) + d1) ) * cm;
          fraction[1][2][i] = (fraction[0][2][i] = (real) ((int)getbits(k) + d1) ) * cm;
          cm=muls[k][scale[x1]];
          fraction[0][0][i] *= cm; fraction[0][1][i] *= cm; fraction[0][2][i] *= cm;
        }
        else
        {
          static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
          unsigned int idx,*tab,m1,m2;
          m1 = scale[x1]; m2 = scale[x1+3];
          idx = (unsigned int) getbits(k);
          tab = (unsigned int *) (table[d1] + idx + idx + idx);
          fraction[0][0][i] = muls[*tab][m1]; fraction[1][0][i] = muls[*tab++][m2];
          fraction[0][1][i] = muls[*tab][m1]; fraction[1][1][i] = muls[*tab++][m2];
          fraction[0][2][i] = muls[*tab][m1]; fraction[1][2][i] = muls[*tab][m2];
        }
        scale+=6;
      }
      else {
        fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] =
        fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;
      }
/* 
   should we use individual scalefac for channel 2 or
   is the current way the right one , where we just copy channel 1 to
   channel 2 ?? 
   The current 'strange' thing is, that we throw away the scalefac
   values for the second channel ...!!
-> changed .. now we use the scalefac values of channel one !! 
*/
    }

    if(sblimit > (SBLIMIT>>fr->down_sample) )
      sblimit = SBLIMIT>>fr->down_sample;

    for(i=sblimit;i<SBLIMIT;i++)
      for (j=0;j<stereo;j++)
        fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;

}

int do_layer2(struct frame *fr,int outmode,struct audio_info_struct *ai)
{
  int clip=0;
  int i,j;
  int stereo = fr->stereo;
  real fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
  unsigned int bit_alloc[64];
  int scale[192];
  int single = fr->single;

  if(stereo == 1 || single == 3)
    single = 0;

  II_step_one(bit_alloc, scale, fr);

  for (i=0;i<SCALE_BLOCK;i++) 
  {
    II_step_two(bit_alloc,fraction,scale,fr,i>>2);
    for (j=0;j<3;j++) 
    {
      if(single >= 0)
      {
        clip += (fr->synth_mono) (fraction[single][j],pcm_sample+pcm_point);
      }
      else {
          clip += (fr->synth) (fraction[0][j],0,pcm_sample+pcm_point);
          clip += (fr->synth) (fraction[1][j],1,pcm_sample+pcm_point);
      }
      pcm_point += fr->block_size;

      if(pcm_point == audiobufsize)
        audio_flush(outmode,ai);
    }
  }

  return clip;
}


